Study of Ag/SiO2 nanosystems by XPS

Silica-supported silver nanocomposites were synthesized by rf sputtering of Ag from Ar plasmas. Depositions were performed on amorphous silica substrates at temperatures as low as 60 °C. As a general rule, a careful choice of the synthesis conditions allowed the obtainment of Ag/SiO2 nanosystems with well-tailored chemico-physical properties. In fact, a proper combination of the applied rf power and total pressure resulted in a fine tailoring of the nanosystem structure and morphology, enabling the preparation of both cluster/island-like systems or continuous thin films. A detailed characterization of the obtained specimens was attained by the combined use of several analytical techniques. While laser reflection interferometry (LRI) was employed for an in situ real-time investigation of growth dynamics, glancing-incidence x-ray diffraction (GIXRD), and transmission electron microscopy (TEM) provided useful information on the system nanostructure. Furthermore, x-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy, and atomic force microscopy (AFM) were used to investigate the chemical composition, optical properties, and surface morphology, respectively. This work has been focused on the XPS characterization of two representative Ag/SiO2 specimens. In particular, detailed scans for the Ag 3d, Ag MVV, Si 2s, O 1s, and C 1s regions and related data for a silver thin film on silica and a discontinuous Ag/SiO2 specimen are presented and discussed.